Cameron van der Burgh, the only other South African competing in the final session of the biennial spectacle, also stepped on the podium, as the national swimming team ended their campaign with five medals.
Le Clos was made to work hard in the men’s 200m butterfly final.
Japan’s Daiya Seto held a narrow lead with 50m remaining, but Le Clos produced his trademark late surge to win gold in 1:48.61, just 0.05 outside his own world record.
Seto settled for second place in 1:48.92.
The 22-year-old South African became the first man to win the 50m, 100m and 200m butterfly titles at the same edition of the biennial showpiece, and also bagged the 200m freestyle crown.
Van der Burgh, meanwhile, shared the silver medal with British teenager Adam Peaty in the men’s 50m breaststroke final.
Both swimmers touched the wall in 25.87 seconds, while Felipe Franca Silva of Brazil set a championship record of 25.63 to secure the gold medal.
READ MORE HERE